Effect of climatic conditions on the performance of a simple basin solar still: a comparative study

Water has always been a source of energy for man. We use solar energy to change salt water into drinking water by solar distillation, a process that started away back in history. Obtaining water is one of the major occupations of rural peoples in the desert areas. The introduction of solar distillation in arid zones of Algeria promise to enhance the quality of life and to improve health standards, including infant survival. Natural fresh water resources are being depleted rapidly, as a result of population growth and socio-economical development. The increasing demand for water puts enormous strain on the underground aquifer, which results in lowering water levels and increasing salt content. The aim of our research has been to study the effect of desert climatic conditions on the performance of a simple basin solar still and a similar one coupled to a flat plate solar collector. Tests were conducted at the solar station of Adrar, an Algeria Saharan site. The performance of the simple still is compared with the coupled one. They were tested for all day productivity under clear sky conditions, with different depth levels of brackish water for winter and summer period and for a three months round test from January to March 2000. Data were taking during all type of sky conditions. A three months round study showed that the productivity of the simple basin and similar coupled to a flat plate solar collector strongly depends on the solar radiation and ambient temperature. The daily still productivity in summer period varies from 4.01 to 4.34 l/m²/d for simple basin solar still and from 8.02 to 8.07 l/m²/d for the coupled one.

The purpose of this study has been to evaluate the productivity of a simple basin hot box and a similar one coupled to a flat plate collector under local climatic conditions of an Algeria Saharan site. For some days in winter and summer, three months round under Algerian arid climatic conditions, the performance of such a simple still and a coupled one were compared. The yield of a coupled still increased that for a simple still. On the basis of the results of this study the following conclusions are reached for Adrar (Algerian Sahara site): Maximum total production of 2.5 cm brackish water depth obtained from January to March for the coupled still is 440.03 kg/m²/d, the total daily production varies from 5.779 to 26.391 MJ/m²/d, and for the same variation of global solar radiation, the productivity of a simple solar still from January to March is 105.95 kg/m²/d. It is observed that the coupled still gives maximum yield at all depth of basin water but not the simple still. Bottom insulation of solar stills increase the productivity. The wind speed has little effect on the production. In arid area solar distillation has potential to provide cheaper distilled water and to reduce the consumption of conventional energy. As a final conclusion we recommend that: Long-term out door tests should be followed over a year for a simple and coupled still. An economic and social assessment of stills should be carried out before it is promoted for field application in arid zones.